At present, with the development of network technologies, people have growing demands on large-volume information (for example, music or video files). The p2p technologies break a conventional client/server (C/S) structure, and p2 p computation is used to randomly select peers, so that data transmission performance is improved, and the cost of the server is also dramatically reduced. However, inmost cases, an optimal peer sequence cannot be found for the peers, thereby causing the deterioration of the data transmission performance or excessive cross-domain traffic. Therefore, optimization of the p2p traffic becomes a central issue in the current p2p technologies.
No matter whether it is a structured p2p or an unstructured p2p, since the peers are randomly selected, a great difference between a logical coverage network and an actual physical bearer network is caused in p2p application. Adjacent nodes in the logical network may span multiple Autonomous System (AS) nodes in an actual route in the physical network, and even span networks of multiple Internet Service Providers (ISPs). In essence, the difference is caused by the reason that network entities in the p2p application fail to know information of lower layer network.
In order to optimize the p2p traffic and to overcome waste of the p2p traffic caused by the random selection of the peers, a method is provided in the prior art, in which a p2p application system performs peer selection according to information of a network provided by an ISP, thereby optimizing the p2p traffic. For example, when a client peer starts a p2p procedure, the client peer requests a peer list from a p2p traffic optimization server, and then the p2p traffic optimization server obtains network topology information of an ISP and returns a preferred peer list to the client peer according to the network topology information of the ISP. The method has the following problems: (1) The ISP needs to provide the network topology information, which easily causes exposure of the ISP network topology information; and (2) a large number of peers request the peer list from the p2p traffic optimization server, which may increase the load on the ISP.
Another method is further provided in the prior art, in which the p2p application system sends a source peer and a destination peer to the p2p traffic optimization server of the ISP, and then the p2p traffic optimization server performs peer selection for the p2p application system according to the network topology information. Such a method has the following problem: the request message from the p2p application system to the p2p traffic optimization server may expose private information of the p2p application system.